The following Power Steering belt was on my car when I purchased it (the top one in the picture below). Per the AIM, it's the correct PN, 3848263 and appears to be Z28 specific, but I'm not sure if it's factory original or a dealer/GM replacement belt.

In the pic below, the top belt is the original; the lower belt is a Quanta reproduction belt. As you can see, the reproduction is quite different than the original GM belt. But that is not to say the Quanta belt is incorrect - it might be a correct factory style belt, maybe there were multiple suppliers/styles, or?